Intermittent Spark!

[jontymiller]

Hi guys

I have put the Mk1 CRM250 back together, everything is sweet except that i have an intermittent spark. The plug sparks every 3rd kick, i have checked the earth the kill switch and it does not have a side stand switch and i am running out of ideas. It is really wierd. Before a stripped it down it ran perfectly started first kick etc.
PLease help me. I have searched the site and come up with nothing

Thanks in advance
Jonty

[Eddie Evans]

Try a new spark plug. For some reason 2 stroke plugs stop working just like that.

[jontymiller]

I have a New Plug, i even tried the old one again. The exact same problem on both plugs.

[knackeredMk1]

Have you tried starting the bike or are you just checking .

When I have looked I have found it very difficult to actually see the spark. I have been caught out several times, when I had rebuilt my engine as was running very rich, by not being able to start the engine due to what in the end turned out to be flooding having spent ages trying to sort out the igintion

If you haven't done it yet, try starting the engine pushing down a hill if you have one available or towing behind another bike .

I am sorry if I'm teaching you to suck eggs .

[fallenmikethebike]

Earth's OK?
mike

[jontymiller]

We kicked it for about half a hour, it fired once. Back Fired twice and kicked back like a four stroke!!!! It is bloody weird!!! Haha i live in Christchurch, no decent hills around hahaha. But yes my next option is to bump start. I don't have the tank on the bike yet. We have been feeding the bike fuel through the carby very slowly. It is has got to be a spark. I can definately see one spark every 3 kicks. So Mike i am going to check the earth and scrape all around it so there is bare metal all around.

I know the one earth is below the seat of the bike and attaches near the top of the frame, is there possibly another earth some where else?
Another thing i will have to check is the kill switch. The side stand switch has been removed and the two live wires joined but the third wire is hanging loose, is that an earth that should be connected up?

Thanks for your help guys

[fallenmikethebike]

Has the Magneto been removed?
Check it for correct alignment, sometimes the Woodruff key has been known to shear off.
It's always a good idea to " lap" the flywheel, and crank taper with some valve grinding paste if the opportunity arises.
Don,t refit it with grease to aid future removal.
Mike

[jontymiller]

The key is ok, i checked the firing mark with the piston, that all seams ok but i am going to have another look at it

[knackeredMk1]

I find once you have kicked it over more than ~ 12 times then it is flooded and best left alone for a while with the plug out.

[jontymiller]

We did not put enough fuel in the carb to flood it that is what we did not put the tank on. We have rebuilt a few 2 strokes and never come across this problem before. I am stuck! i might go over the electrics from the front to the back. We let you know how it goes.

[fallenmikethebike]

The key is ok, i checked the firing mark with the piston, that all seams ok but i am going to have another look at it

Timing is fixed, so, that should be right.
HT lead, at the cap, unscrew and check for white deposits, cut back , just enough to get to clean wire.
The side stand wires, the 2 important ones seem ok, but it's worth just popping the other one into a strip connector, and taping up.
Mike

[knackeredMk1]

The issue seems to be that it only sparks every 3rd kick. I don't know of any reason why this should be so and FMtB has run through the most common ignition/electrical faults that could cause an intermittent spark - But not 'every 3rd kick'. This makes me think that we are not getting the whole information/detail and this is why I keep pushing the flooding point.

One final point from this direction - If you haven't flooded it after the kicking it for half an hour there is no way that there was enough fuel in the carb.

[jontymiller]

Yes i do realise what you are saying, and i appreciate your help.
What happened we kicked the bike and could not get it to fire so it flooded itself, we then pulled the plug out of the bike and cut the fuel and kicked it to get most of the fuel out of the barrel. We then attached the plug to the HT lead and kicked the bike to see the spark by putting the plug against the top of the head. This is when we noticed the spark problem(sparking every third kick). It was dark so the spark was easily noticable. That is what has got me stumped!

[josh mk 2 crm]

i had exatly the same problem with my mk 2 turned out to be a nackerd cdi and reg/rec :(
do the 12 volt test and see if it works!
a nackerd cdi will let u know by smoking and sizzling! :)

hope this helps

[fallenmikethebike]

Reg/Rec/CDI, ouch, any overtime going at work?
Mike